Titanium bearing material flow control in the manufacture of titianium tetrachloride using a combination of feedback and feed forward responses

ABSTRACT

This disclosure relates to process for controlling chlorination reactions in manufacturing titanium tetrachloride in a fluidized bed reactor, optionally followed by processing to form a titanium product comprising a minor amount of silica, the process comprising: (a) feeding carbonaceous material, titanium bearing material comprising an amount of silica, and chlorine to the fluidized bed reactor to form a gaseous stream, and condensing the gaseous stream to form titanium tetra-chloride, a non-condensed gas stream and a condensable product stream, wherein at least one of the titanium tetrachloride and the non-condensed gas stream comprise silicon tetrachloride; (b) analyzing the non-condensed gas stream, the titanium tetrachloride or both, to determine the analyzed concentration of silicon tetrachloride; (c) identifying a set point concentration of silicon tetrachloride based on the desired amount of silica in the titanium product; (d) calculating the difference between the analyzed concentration of silicon tetra-chloride and the set point concentration of silicon tetrachloride; (e) measuring the titanium tetrachloride flow to a processing reactor that releases chlorine; (f) measuring the flow of fresh chlorine added to the fluidized bed; (g) measuring the flow of the titanium bearing material added to the fluidized bed reactor and establishing a historic average flow of the titanium bearing material added to the fluidized bed reactor; (h) calculating the chlorine released from the titanium tetrachloride that is processed using the titanium tetrachloride flow data from step (e); (i) calculating the total chlorine flow to the fluidized bed reactor by adding the chlorine flow in step (f) to the chlorine flow calculated in step (h) and establishing a historic average chlorine flow; (j) calculating a unit titanium bearing material consumption per unit chlorine; (k) calculating an estimated current consumption rate of titanium bearing material based on the total chlorine flow from step (i) times the unit titanium bearing material consumption per unit chlorine from step (j); and (l) generating a signal based on difference generated in step (d) that provides a feedback response and combining this to the estimated current consumption rate of titanium bearing material from step (k) to provide a feed forward response to control the flow of the titanium bearing material into the fluidized bed reactor.

FIELD OF THE DISCLOSURE

The present disclosure relates to a process for manufacturing titaniumtetrachloride, and in particular to a control process for controllingthe flow of titanium bearing material into the fluidized bed reactor andthereby the amount of silicon in the final product.

BACKGROUND OF THE DISCLOSURE

The process for chlorinating titanium containing materials in afluidized bed reactor is known. Suitable processes are disclosed in thefollowing U.S. Pat. Nos. 2,701,179; 3,883,636; 3.591333; and 2,446,181.In such processes, particulate coke, particulate titanium bearingmaterials, chlorine and optionally oxygen or air are fed into a reactionchamber, and a suitable reaction temperature, pressure and flow ratesare maintained to sustain the fluidized bed. Gaseous titaniumtetrachloride and other metal chlorides are exhausted from the reactionchamber. The gaseous titanium tetrachloride so produced can then beseparated from the other metal chlorides and exhaust gas and used toproduce titanium dioxide, titanium metal or titanium containing product.

In the chlorination process to prepare titanium tetrachloride, TiCl₄, ina fluidized bed reactor, it is desirable to reduce or control theformation of excess silicon tetrachloride and other undesirablechlorinated organic species. Silicon tetrachloride, SiCl₄, contaminationof titanium tetrachloride impacts a variety of quality parameters, suchas particle size distribution and primary particle size (indicated bycarbon black undertone) of the titanium dioxide produced by oxidation ofthe TiCl₄. Minimizing or controlling the silica contamination allows forimproved performance of the TiO₂ product.

A need exists for a control process that detects the presence of excessSiCl₄, and therefore excess silica in the final product, and that iscapable of correcting the problem.

SUMMARY OF THE DISCLOSURE

In a first aspect, the disclosure provides a process for controllingchlorination reactions in manufacturing titanium tetrachloride in afluidized bed reactor, optionally followed by processing to form atitanium product comprising an amount, typically a minor amount, ofsilica, the process comprising:

(a) feeding carbonaceous material, titanium bearing material comprisingan amount of silica, and chlorine to the fluidized bed reactor to form agaseous stream, and condensing the gaseous stream to form titaniumtetrachloride, a non-condensed gas stream and a condensable productstream, wherein at least one of the titanium tetrachloride and thenon-condensed gas stream comprise silicon tetrachloride;

(b) analyzing the non-condensed gas stream, the titanium tetrachlorideor both, to determine the analyzed concentration of silicontetrachloride;

(c) identifying a set point concentration of silicon tetrachloride basedon the desired amount of silica in the titanium product;

(d) calculating the difference between the analyzed concentration ofsilicon tetrachloride and the set point concentration of silicontetrachloride;

(e) measuring the titanium tetrachloride flow to a processing reactorthat releases chlorine;

(f) measuring the flow of fresh chlorine added to the fluidized bed;

(g) measuring the flow of the titanium bearing material added to thefluidized bed reactor and establishing a historic average flow of thetitanium bearing material added to the fluidized bed reactor;

(h) calculating the chlorine released from the titanium tetrachloridethat is processed using the titanium tetrachloride flow data from step(e);

(i) calculating the total chlorine flow to the fluidized bed reactor byadding the chlorine flow in step (f) to the chlorine flow calculated instep (h) and establishing a historic average chlorine flow;

(j) calculating a unit titanium bearing material consumption per unitchlorine;

(k) calculating an estimated current consumption rate of titaniumbearing material based on the total chlorine flow from step (i) timesthe unit titanium bearing material consumption per unit chlorine fromstep (j); and

(l) generating a signal based on difference generated in step (d) thatprovides a feedback response and combining this with the estimatedcurrent consumption rate of titanium bearing material from step (k) toprovide a feed forward response by adding together, multiplying or otheralgorithm to control the flow of the titanium bearing material into thefluidized bed reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 sets forth a simplified schematic flow diagram of an embodimentof this disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Carbonaceous material, titanium bearing material containing someimpurities, chlorine, and optionally oxygen or air are fed into afluidized bed reactor. Typical conditions and specifications forfluidized beds useful for this disclosure are as follows: reactiontemperature of about 900° C. to 1300° C., pressure of about 1-3atmospheres, and a reactor with multiple jets in or near the base.Typically, the point of introduction of the chlorine will be locatedwithin about 0 to about 10 feet (about 0 to about 3 m), more typicallyabout 0 to about 8 feet (about 0 to about 2.4 m) and most typicallyabout 0 to about 5 feet (about 0 to about 1.5 m) of the base of thereactor. A most typical location is in the base of the reactor.

The titanium bearing material can be any suitable titanium sourcematerial such as titanium containing ores including rutile, ilmenite oranatase ore; beneficiates thereof; titanium containing byproducts orslags; and mixtures thereof. Ordinarily, the titanium bearing materialcontains iron oxide in the amount of about 0.5-50%, and typically up toabout 20% by weight, based on the total weight of the titanium bearingmaterial. This material also typically contains silica. The silica canbe present in any form, such as in a silica-containing material or ametallic oxide, but is usually in the form of one or more naturallyoccurring forms such as sand, quartz, silicates, silica. SiO2, andCrystobalite. The silica can be in the amount of about 0 to about 25%,and typically about 0.5 to about 1.5%, based on the total weight of thetitanium bearing material. The amount of silicon in the titanium bearingmaterial can be determined by XRF analysis or wet chemistry methods orother suitable analytical procedure. The silica can be the source ofsilicon tetrachloride in the gaseous stream of the fluidized bedreactor.

Suitable carbonaceous material for use in this disclosure is anycarbonaceous material which has been subjected to a coking process.Typical is coke or calcined coke which is derived from petroleum or coalor mixtures of such cokes.

As shown in FIG. 1, a titanium bearing material 10 is fed through acontrol device 13 to the fluidized bed reactor 14. Carbonaceous material11 is fed directly into the fluidized bed reactor 14. Alternately,carbonaceous material 11 may be fed to the fluidized bed reactor 14 viaa control device. The titanium bearing material and the carbonaceousmaterial can also be combined prior to being fed to the fluidized bedreactor 14. The chlorine 12 is fed into the fluidized bed reactor 14with a recycle stream 27 that recycles chlorine liberated during theprocessing, typically oxidation, of TiCl₄ to TiO₂ in the TiCl₄processing reactor 19, typically an oxidation reactor or if chlorine isreleased during other processing. Chlorine can also be added atdifferent points in the fluidized bed reactor using techniques known toone skilled in the art. Gaseous reaction products from the fluidized bedreactor are cooled in condenser(s) 15, in stages, to first condense andremove iron and metal chlorides other than titanium tetrachloride 22.The iron and metal chlorides form the condensable product stream 23. Theremaining product from the reactor is then cooled to condense titaniumtetrachloride 22 leaving a non-condensed gas stream 21 comprising N₂.COS, SO₂, CO, CO₂, and HCl and other components such as SiCl₄. A portionor all of the non-condensed gas stream 21, i.e., a sample stream, issent to an analytical device or analyzer 16 such as a spectrometer,spectrophotometer and chromatograph. Alternately, the titaniumtetrachloride 22 may be sampled using the titanium tetrachloride samplestream 22 a or both streams may be sampled and analyzed.

A sampling system may be required depending on the type of analyzerchosen, the condition of the non-condensed gas and/or the placement ofthe analyzer. The analytical device can be in-line, meaning installeddirectly in the path of the stream to be analyzed, typically thenon-condensed gas stream 21, or on-line, meaning a portion of the streamto be analyzed, typically the non-condensed gas stream 21, is directedaway from the main process stream and toward the analytical device oroff-line meaning a sample is collected and analyzed discretely. Thesample stream is analyzed for SiCl₄ concentration. The analysis is ableto proceed quickly, semi continuously and quantitatively. Suitable meansof analysis include, but are not limited to spectroscopy, spectrometryand chromatography. Typically, a spectroscopic method is used to analyzethe SiCl₄ concentration of the non-condensed gas stream 21, titaniumtetrachloride 22 or both streams. More typically, infrared spectroscopyand most typically, Fourier transform infrared spectroscopy is used asthe analytical method. Optionally, any portion of the sample stream canbe returned to the stream being analyzed, typically the non-condensedgas stream 21, if desired, or sent to a process ventilation system.

For purposes of TiO2 bearing material feed control only one SiCl₄measurement method and one sample location can be used or a combinationof feed back controllers can be used such as in a cascade controlscheme.

A first signal 24 (electrical, pneumatic, digital, manual, etc.) isgenerated from the analysis that is related to the SiCl₄ concentrationin the non-condensed gas stream 21. Alternately, the first signal 24 isgenerated from the analysis that is related to the SiCl₄ concentrationin the titanium tetrachloride or both the non-condensed gas stream andthe titanium tetrachloride. The signal proceeds to a control system(such as a distributed control system or other feedback control system17) where its value is compared to a set point 18 or determined if it iswithin a set range. The set point can be a single value reflecting anacceptable silicon tetrachloride concentration or the upper limit of arange of values within which an acceptable silicon tetrachlorideconcentration can be. This set point 18 is a predetermined or a presetvalue meaning it is a desired or acceptable SiCl₄ concentration. TheSiCl₄ concentration is dependent on the desired concentration of siliconin the titanium product. The SiCl₄ concentration in the non-condensedgas stream 21 is related to the amount of silicon in the titaniumproduct. The relationship between the SiCl₄ measured in thenon-condensed gas stream and the titanium product will be dependent onoperating factors such as the temperature and pressure upstream of theanalysis. Typically if operating the equipment upstream near −10°centigrade, about 0 to about 0.3 mole % of the total gases in thenon-condensed gas stream will be SiCl₄. Subtracting the SiCl₄concentration from the analysis from the predetermined acceptable mole %SiCl₄ set point concentration can provide the SiCl₄ concentrationdifference that will generate the signal that adjusts the flow of thetitanium bearing material 10 to the fluidized bed reactor 14. Underthese conditions the full range of concentration of SiCl₄ is about 0 toabout 0.3 mole %, typically about 0.01 to about 0.1 mole % and moretypically about 0.01 to about 0.05 mole %, corresponding to about 0 toabout 0.3 weight % SiO₂, typically about 0.0 to about 0.1 mole % SiO₂and more typically 0.01-0.06 mole % SiO₂, respectively in the oxidizedproduct. However, silicon content can vary significantly, for example,based on the temperature and pressure upstream, and these differencesmust be taken into account when determining a set point for SiCl₄concentration in the non-condensed gas stream 21. The SiCl₄concentration set point has the broad limits of about 0.01 to about 0.25mole % based on the total SiCl₄ content of the non-condensed gas stream21. The set point can be any desired value within this range. Typically,the SiCl₄ concentration set range is about 0.005 to about 0.05 mole %and more typically about 0.01 to about 0.04 mole % of the total contentnon-condensed gas stream 21. It is important that the lower limit to theset range of SiCl₄ concentration is not below the detectability limit ofthe analytical device being used.

If the controlled variable does not equal the set point or is outside ofthe set range, then the difference between the measured controlledvariable and set point concentration or concentration range upper limitis determined. A second signal (electrical, pneumatic, digital, manual,etc.) corresponding to this difference is generated either manually orby a suitable

feedback controller 17 such as, for example, a proportional, aproportional integral or a proportional integral derivative actioncontroller or other suitable computer software or algorithm thatprovides a feedback response to the control device 13 which will cause achange in the amount of titanium bearing material being added to thefluidized bed reactor by making a change, typically a proportionalchange, in the flow rate of the titanium bearing material to thefluidized bed reactor 14. With continuous or discrete monitoring of thecontrolled variable, the amount of the titanium bearing material addedto the fluidized bed reactor can be changed until the controlledvariable reaches the set point or is within the set range, as specifiedfor the process. If the SiCl₄ concentration in the non-condensed gasstream 21 is determined to be outside of the set range, appropriatechanges to the amount of the titanium bearing material being added tothe fluidized bed reactor 14 will be implemented. For example, if it isfound that the analyzed SiCl₄ concentration is above the set point, theamount of the titanium bearing material being added to the fluidized bedreactor 14 will be increased by an amount proportional to the amount ofSiCl₄ above the upper limit or set point. Alternately, the amount oftitanium bearing material can be decreased if the silicon tetrachlorideconcentration analyzed is below the set point.

The process further includes measuring the titanium tetrachloride flowto the titanium tetrachloride processing reactor 19, typically anoxidation reactor, using a flow transmitter 28 in the feed line to thereactor. Flow of fresh chlorine added to the fluidized bed reactor ismeasured using a flow transmitter(s) 29 wherever chlorine is added intothe fluidized bed. The flow of the titanium bearing material added tothe fluidized bed reactor can be measured using X-ray fluorescence orother suitable analytical technique and any suitable flow measurementtechnique. A historic average flow of the titanium bearing material isestablished by averaging the flow of titanium bearing material to thefluidized bed reactor over a suitably long period of time so as todampen out the impact of minor fluctuations in the process. A suitabletime period is a month of fluidized bed operation. The chlorine releasedfrom the titanium tetrachloride that is processed, typically oxidized,is calculated using the titanium tetrachloride flow data from step (d)using the molecular weights of titanium tetrachloride and chlorine. Thetotal chlorine flow to the chlorinator is calculated by adding thechlorine flow of the freshly added chlorine to the chlorine releasedduring processing of the titanium tetrachloride that is recycled back tothe fluidized bed 14 via recycle gas line 27. A historic averagechlorine flow is established by averaging the flow of chlorine to thefluidized bed reactor over a suitably long period of time so as todampen out the impact of minor fluctuations in the process. A suitabletime period is a month of fluidized bed operation.

In step (j), the unit titanium bearing material consumption per unitchlorine can then be calculated. This can be done based on thecomposition of the titanium bearing material and the known chemistry ofthe conversion of the titanium bearing material chemical conversion tochlorides or using the following equation:

(unit titanium bearing material consumption per unit chlorine)=(historicaverage flow of the titanium bearing material from step (g))/(historicaverage chlorine flow from step (i)).

This number is dependent on the % titanium dioxide ore being used.

In step (k), the estimated current consumption rate of titanium bearingmaterial is calculated based on the total chlorine flow from step (i)times the unit titanium bearing material consumption per unit chlorinefrom step (j). A feed forward response is generated by the feed forwardcontroller 30, using the estimated current consumption rate of titaniumbearing material from step (k). This is dependent on the size of theplant.

The feed forward response is provided by a feed forward controllerselected from the group consisting of a proportional action controller,a proportional integral action controller, a proportional integralderivative action controller; or suitable computer software or algorithmthat provides a feed forward response to a control device.

The signals from the feedback and feed forward responses are usedcontrol the flow of the titanium bearing material 10 into the fluidizedbed reactor 14. In one embodiment, the signal generated in step (l) isadded to the estimated current consumption rate of titanium bearingmaterial to control the flow of the titanium bearing material into thefluidized bed reactor. In another embodiment, the signal generated instep (l) is multiplied to the estimated current consumption rate oftitanium bearing material to control the flow of the titanium bearingmaterial into the fluidized bed reactor. Alternately, other algorithmscan be used.

A typical titanium product produced from the titanium tetrachloride ofthis disclosure is titanium dioxide in which case the fluidized bedreactor can be followed by oxidation to form a suitable titanium dioxideproduct such as pigmentary titanium dioxide or titanium dioxidenanoparticles. Other titanium products are also contemplated such astitanium metal which can be made from the titanium tetrachloride by aknown processes such as the Kroll and Hunter processes. The process ofthis disclosure which permits control of the silicon tetrachloride canproduce a useful titanium dioxide product having a low and controlledsilica concentration.

Assuming there is no separate source of SiCl₄ added directly to theTiCl₄ prior to the oxidation reactor or there is no SiCl₄ added directlyto the TiCl₄ oxidation reactor, the correlation between silicontetrachloride concentration in the titanium tetrachloride or theconcentration of SiCl₄ measured in the non condensed stream 21 andsilica (SiO₂) concentration in the titanium dioxide directly withdrawnfrom the oxidation process without any further treatment (“base titaniumdioxide) is very good. Thus, the process of the disclosure can reduce orcontrol the base titanium dioxide silica concentration in a range fromabout 0.0 to 0.3 weight %, typically, the SiO₂ concentration range isabout 0 to about 0.1 weight % and more typically about 0.01 to about0.06 weight % based on the analytical device or analyzer 20 such as aspectrometer, spectrophotometer and chromatograph. If a separate sourceof SiCl₄ is added directly to the TiCl₄ prior to the oxidation reactoror SiCl₄ is added directly to the TiCl₄ oxidation reactor, the standarddeviation of the silica in the final product can be improved bycontrolling the SiCl₄ in the titanium tetrachloride 22 or thenon-condensed stream 21.

The disclosure can additionally provide an improved process forcontrolling chlorination reactions in the manufacture of titaniumtetrachloride in a fluidized bed reactor.

To give a clearer understanding of the disclosure, the following exampleis construed as illustrative and not limitative of the underlyingprinciples of the disclosure in any way whatsoever.

EXAMPLE

SiCl₄ in the non-condensed gas stream is related to the SiCl₄ in thecondensed TiCl₄. A portion of the SiCl₄ in the condensed TiCl₄ isoxidized to SiO₂ in the base TiO₂ pigment. The correlation between theSiCl₄ in the non-condensed gas stream and the SiO₂ in the base TiO₂pigment is very good.

SiO₂ concentration in the base pigment is known to correlate with avariety of quality parameters, such as particle size distribution andprimary particle size (indicated by carbon black undertone) of thetitanium dioxide produced by oxidation of the TiCl₄. By controlling theSiCl₄ concentration, variability in these parameters can be reduced andthe product quality improved.

Over a period of four and a half months experimentation was carried outin a plant to demonstrate the effect of automated SiCl₄ control. Fourhundred and eighty three consecutive product samples were collect andanalysed for SiO₂. This was compared with 483 samples prior to anysilica control. The variability in the product SiO₂ concentration wasmeasured and provided in Table 1.

TABLE 1 Base TiO₂ Product SiO₂ Concentration Standard Deviation TiO₂Bearing Material Feed Control Method 0.0463 SiCl₄ Based TiO₂ BearingMaterial Feed 0.0228 Control Method Reduction in Base Pigment SiO₂Standard 51% DeviationThe previous TiO₂ bearing material feed control method noted in Table 1was based on reactions in the chlorinator including theoreticalconsumption rate of titanium bearing materials and inferential chlorinedischarge rate.From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of the disclosure, and withoutdeparting from the spirit and scope thereof, can make various changesand modification of the disclosure to adapt it to various usages andconditions.

Having thus described and exemplified the disclosure with a certaindegree of particularity, it should be appreciated that the followingclaims are not to be limited but are to be afforded a scope commensuratewith the wording of each element of the claims and equivalents thereof.

1. A process for controlling chlorination reactions in manufacturingtitanium tetrachloride in a fluidized bed reactor, optionally followedby processing to form a titanium product comprising a minor amount ofsilica, the process comprising: (a) feeding carbonaceous material,titanium bearing material comprising an amount of silica, and chlorineto the fluidized bed reactor to form a gaseous stream, and condensingthe gaseous stream to form titanium tetrachloride, a non-condensed gasstream and a condensable product stream, wherein at least one of thetitanium tetrachloride and the non-condensed gas stream comprise silicontetrachloride; (b) analyzing the non-condensed gas stream, the titaniumtetrachloride or both, to determine the analyzed concentration ofsilicon tetrachloride; (c) identifying a set point concentration ofsilicon tetrachloride based on the desired amount of silica in thetitanium product; (d) calculating the difference between the analyzedconcentration of silicon tetrachloride and the set point concentrationof silicon tetrachloride; (e) measuring the titanium tetrachloride flowto a processing reactor that releases chlorine; (f) measuring the flowof fresh chlorine added to the fluidized bed; (g) measuring the flow ofthe titanium bearing material added to the fluidized bed reactor andestablishing a historic average flow of the titanium bearing materialadded to the fluidized bed reactor; (h) calculating the chlorinereleased from the titanium tetrachloride that is processed using thetitanium tetrachloride flow data from step (e); (i) calculating thetotal chlorine flow to the fluidized bed reactor by adding the chlorineflow in step (f) to the chlorine flow calculated in step (h) andestablishing a historic average chlorine flow; (j) calculating a unittitanium bearing material consumption per unit chlorine; (k) calculatingan estimated current consumption rate of titanium bearing material basedon the total chlorine flow from step (i) times the unit titanium bearingmaterial consumption per unit chlorine from step (j); and (l) generatinga signal based on difference generated in step (d) that provides afeedback response and combining this to the estimated currentconsumption rate of titanium bearing material from step (k) to provide afeed forward response to control the flow of the titanium bearingmaterial into the fluidized bed reactor.
 2. The process of claim 1wherein the analyzed concentration of silicon tetrachloride is greaterthan the set point concentration of silicon tetrachloride.
 3. Theprocess of claim 1 wherein the analyzed concentration of silicontetrachloride is less than the set point concentration of silicontetrachloride.
 4. The process of claim 2 wherein the analyzedconcentration of silicon tetrachloride is greater than the set pointconcentration of silicon tetrachloride and the feedback responsecomprises increasing the amount of titanium bearing material beingintroduced into the fluidized bed reactor.
 5. The process of claim 3wherein the analyzed concentration of silicon tetrachloride is less thanthe set point concentration of silicon tetrachloride and the feedbackresponse comprises decreasing the amount of titanium bearing materialbeing introduced into the fluidized bed reactor.
 6. The process of claim1 wherein the analyzed concentration of silicon tetrachloride isdetermined by analyzing the non-condensed gas stream.
 7. The process ofclaim 1 wherein the analyzed concentration of silicon tetrachloride isdetermined by analyzing the titanium tetrachloride.
 8. The process ofclaim 1 wherein analyzing the non-condensed gas stream is achieved byspectroscopy, spectrometry or chromatography.
 9. The process of claim 8wherein analyzing the non-condensed gas stream is by infraredspectroscopy.
 10. The process of claim 1 wherein the silicontetrachloride is present in the non-condensed gas stream in the amountof about 0 to about 0.3 mole %, based on the total weight of theanalyzed stream.
 11. The process of claim 10 wherein the silicontetrachloride is present in the non-condensed gas stream in the amountof about 0.01 to about 0.1 mole %, based on the total weight of theanalyzed stream.
 12. The process of claim 11 wherein the silicontetrachloride is present in the non-condensed gas stream in the amountof about 0.01 to about 0.05 mole %, based on the total weight of theanalyzed stream.
 13. The process of claim 1 wherein the set point ofsilicon tetrachloride is about 0.01 to about 0.25 mole %.
 14. Theprocess of claim 1 wherein the signal is electrical, pneumatic, digitalor manual.
 15. The process of claim 1 wherein the feedback response isprovided by a feedback controller selected from the group consisting ofa proportional, a proportional integral action controller, aproportional integral derivative action controller; or suitable computersoftware or algorithm that provides a feedback response to a controldevice.
 16. The process of claim 1 wherein the processing reactor is anoxidation reactor and the titanium tetrachloride is oxidized to atitanium product comprising titanium dioxide.
 17. The process of claim 1wherein the feed forward response is provided by a feed forwardcontroller selected from the group consisting of a proportional actioncontroller, a proportional integral action controller, a proportionalintegral derivative action controller; or suitable computer software oralgorithm that provides a feed forward response to a control device.